STRUCTURE OF THE REACTION PRODUCT OF 4-HYDROXY-2,3-DIOXO-4-PHENYLBUTANOIC ACID 1,4-LACTONE WITH o-PHENYLENEDIAMINE

Article abstract of DOI:10.1016/S0008-6215(00)90728-6

Examination of the sructure of the yellow product (5a), obtained by treating 4-hydroxy-2,3-dioxo-4-phenylbutanoic acid 1,4-lactone (4-phenyl-2,3-dioxobutyro-1,4-lactone) with two moles of o-phenylenediamine, by high-resolution 1H-, 13C-, and 15N-n.m.r. spectroscopy, as well as by electron-impact mass spectrometry, confirmed without ambiguity the structure of the product as the quinoxaline amide 5a.When 4-hydroxy-2,3-dioxo-4-phenylbutanoic acid 1,4-lactone is treated with o-phenylenediamine, the Schiff base is first formed, which is then converted into a quinoxaline lactone (6a).The excess of o-phenylenediamine then converted the quinoxaline lactone (6a) into the yellow product (5a).